A character's maximum health is normally equal to their vitality.
A character's maximum health determines how much damage they can take before they are downed.
Whenever a character takes damage, reduce their current health by the damage.
When a character's health is 0 or less, that character is downed.
Whenever a downed character takes damage, reduce their maximum health by the damage.
If a character's maximum health is 0 or less, that character dies.
Maximum health can only be restored by resting, at a rate of 1d4 per day with no other strenuous activity.